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How to programmatically add a function to an Object like the following example

How to programmatically add an Object method like the following example.
let object2 = {
name: "object2",
onExecute() {
const input1 = this.getInputData(0)
// do something
}
}
I'm trying to figure out how to programmatically add a method to the object. I need to end up with the object2 example.
I tried the following, but it does not seem to be correct.
object2.onExecute = () => {
const input1 = this.getInputData(0)
// do something
}

In the end I did this:
object2.onExecute = function () {
const input1 = this.getInputData(0)
// do something
}
and it worked as expected.

How to access specific properties in a multiple objects using JS

Here is my object:
$scope.info = [];
$scope.info = [{"name":"kanye","size":"","folder":"Folder"},{"name":"west","size":"","folder":"Folder"}]
$scope.infoObj = $scope.info.name;
console.log($scope.infoObj);
This return me Undefined. The response should be like this:
[{"name":kanye},{"name":west}]
But how to access the specific properties from a multiple object using angularJS or jquery/js?

This should solve the problem:
$scope.infoObj = $scope.info.map(function(obj){
var x = {};
x['name'] = obj['name'];
return x;
})
for ES6, it can be simplified to:
$scope.infoObj = $scope.info.map(x => ({name:x['name']}))

You can actually do a little bit of refactoring to make your code a little cleaner and more readable. Instead of setting your info value twice, set it once, and add the objects in each line after.
Like this:
$scope.info = [];
$scope.info.push({
"name":"kanye",
"size":"",
"folder":"Folder"
});
$scope.info.push({
"name":"west",
"size":"",
"folder":"Folder"
});
See how clean that is? Now it should be fairly obvious that info is an Array of objects, so doing $scope.info.name won't work. What I would recommend is creating a lookup function that can help grab a list based on the key you provide it.
Something like this:
function lookup(key) {
var result = [];
for (var i = 0; i < $scope.info.length; i++) {
var object = {};
object[key] = $scope.info[i][key];
result.push(object);
}
return result;
}
And then call it like this:
$scope.infoObj = lookup('name');
console.log($scope.infoObj);

Returning a reference in JavaScript

Here is the code:
http://jsfiddle.net/GKBfL/
I am trying to get collection.prototype.add to return a reference such that the final alert will display testing, testing, 123, testing. Is there a way to accomplish what I'm trying to do here?
HTML:
<span id="spantest">testing, testing, 123, testing</span>​
JavaScript:
var collection = function () {
this.items = {};
}
collection.prototype.add = function(sElmtId) {
this.items[sElmtId] = {};
return this.items[sElmtId];
}
collection.prototype.bind = function() {
for (var sElmtId in this.items) {
this.items[sElmtId] = document.getElementById(sElmtId);
}
}
var col = new collection();
var obj = {};
obj = col.add('spantest');
col.bind();
alert(obj.innerHTML);​

You problem is this line:
this.items[sElmtId] = document.getElementById(sElmtId);
This overwrites the object currently assigned to this.items[sElmtId] with the DOM node. Instead, you should assign the node to a property of that object:
this.items[sElmtId].node = document.getElementById(sElmtId);
That way, obj.node will always refer to the current node:
alert(obj.node.innerHTML);
DEMO
Side note: The problem with your fiddle is also that you execute the code when the DOM is not built yet (no wrap (head)), so it cannot find #spantest. You have to run the code once the DOM is ready, either no wrap (body), onDomRead or onLoad.

Creating a reference like you need is impossible in JavaScript. The closest thing you can get is either a nested or closed object, or just copying it over, like so:
var collection = function() {
this.items = {};
};
collection.prototype.add = function(sElmtId) {
return this.items[sElmtId] = {};
};
collection.prototype.bind = function() {
for(var sElmtId in this.items) {
var element = document.getElementById(sElmtId);
for(var x in element) {
this.items[sElmtId][x] = element[x];
}
}
};
var col = new collection();
var obj = {};
obj = col.add('spantest');
col.bind();
alert(obj.innerHTML);
But it won't be truly "bound". You'll have to use nested objects if you need that kind of functionality, and it will probably defeat the point of your syntactic sugar.
http://jsfiddle.net/GKBfL/7/

Javascript array is undefined... and I'm not sure why

I'm trying to translate a PHP class into JavaScript. The only thing I'm having trouble with is getting an item out of an array variable. I've created a simple jsfiddle here. I cannot figure out why it won't work.
(EDIT: I updated this code to better reflect what I'm doing. Sorry for the previous mistake.)
function tattooEightBall() {
this.subjects = ['a bear', 'a tiger', 'a sailor'];
this.prediction = make_prediction();
var that = this;
function array_random_pick(somearray) {
//return array[array_rand(array)];
var length = somearray.length;
var random = somearray[Math.floor(Math.random()*somearray.length)];
return random;
}
function make_prediction() {
var prediction = array_random_pick(this.subjects);
return prediction;
}
}
var test = tattooEightBall();
document.write(test.prediction);
​

Works fine here, you are simple not calling
classname();
After you define the function.
Update
When you make a call to *make_prediction* , this will not be in scope. You are right on the money creating a that variable, use it on *make_prediction* :
var that = this;
this.prediction = make_prediction();
function make_prediction() {
var prediction = ''; //initialize it
prediction = prediction + array_random_pick(that.subjects);
return prediction;
}
You can see a working version here: http://jsfiddle.net/zKcpC/
This is actually pretty complex and I believe someone with more experience in Javascript may be able to clarify the situation.
Edit2: Douglas Crockfords explains it with these words:
By convention, we make a private that variable. This is used to make
the object available to the private methods. This is a workaround for
an error in the ECMAScript Language Specification which causes this to
be set incorrectly for inner functions.
To see the complete article head to: http://javascript.crockford.com/private.html

You never call classname. Seems to be working fine.

Works for me:
(function classname() {
this.list = [];
this.list[0] = "tiger";
this.list[1] = "lion";
this.list[2] = "bear";
function pickone(somearray) {
var length = somearray.length;
var random = somearray[Math.floor(Math.random()*length)];
return random;
}
var random_item = pickone(this.list);
document.write(random_item);
}());
Were you actually calling the classname function? Note I wrapped your code block in:
([your_code]());

I'm not sure what you're trying to accomplish exactly with the class structure you were using so I made some guesses, but this code works by creating a classname object that has instance data and a pickone method:
function classname() {
this.list = [];
this.list[0] = "tiger";
this.list[1] = "lion";
this.list[2] = "bear";
this.pickone = function() {
var length = this.list.length;
var random = this.list[Math.floor(Math.random()*length)];
return random;
}
}
var cls = new classname();
var random = cls.pickone();
You can play with it interactively here: http://jsfiddle.net/jfriend00/ReL2h/.

It's working fine for me: http://jsfiddle.net/YznSE/6/ You just didn't call classname(). If you don't call it, nothing will happen ;)

Make it into a self-executing function like this:
(function classname() {
this.list = [];
this.list[0] = "tiger";
this.list[1] = "lion";
this.list[2] = "bear";
function pickone(somearray) {
var length = somearray.length; //<---WHY ISN'T THIS DEFINED??
var random = somearray[Math.floor(Math.random() * length)];
return random;
}
var random_item = pickone(this.list);
document.write(random_item);
})();

var test = tattooEightBall();
document.write(test.prediction);
Should be:
var test = new tattooEightBall(); //forgot new keyword to create object
document.write(test.prediction()); // forgot parens to fire method
and:
this.prediction = make_prediction();
Should be:
this.prediction = make_prediction;

Use variable's value as variable in javascript

I have a variable with a value, let's say
var myVarMAX = 5;
In HTML I have an element with id="myVar".
I combine the id with the string MAX (creating a string myVarMAX). My question is how can I use this string to access a variable with the same name?

You COULD use eval, but if you have the var in the window scope, this is better
var myVarMAX = 5;
var id="MAX"; // likely not in a var
alert(window["myVar"+id]); // alerts 5
However Don't pollute the global scope!
A better solution is something like what is suggested in the link I posted
var myVars = {
"myVarMin":1,
"myVarMax":5,
"otherVarXX":"fred"
} // notice no comma after the last var
then you have
alert(myVars["myVar"+id]);

Since this post is referred to often, I would like to add a use case.
It is probably often a PHP programmer who gives Javascript/Nodejs a try, who runs into this problem.
// my variables in PHP
$dogs = [...]; //dog values
$cats = [...]; //cat values
$sheep = [...]; //sheep values
Let's say I want to save them each in their own file (dogs.json, cats.json, sheep.json), not all at the same time, without creating functions like savedogs, savecats, savesheep. An example command would be save('dogs')
In PHP it works like this:
function save($animal) {
if(!$animal) return false;
file_put_contents($animal.'.json', json_encode($$animal));
return true;
}
In Nodejs/Javascript it could be done like this
// my variables in NodeJS/Javascript
let dogs = [...]; //dog values
let cats = [...]; //cat values
let sheep = [...]; //sheep values
function save(animal) {
if (!animal) return false;
let animalType = {};
animalType.dogs = dogs;
animalType.cats = cats;
animalType.sheep = sheep;
fs.writeFile(animal + '.json', JSON.stringify(animalType[animal]), function (err){
if (err) return false;
});
return true;
}